A pot experiment with long-term flooding and drought was conducted to study the root growth characteristics of three typical hygrophytes (Artemisia selengensis, Carex cinerascens, and Phalaris arundinacea) in beach wetland of Poyang Lake. As for C. cinerascens and P. arundinacea, their main root length and weight as well as fibrous root weight and length under long term flooding were obviously greater than those under drought. However, A. selengensi showed an opposite trend to C. cinerascens and P. arundinacea. No significant differences were observed in the main root and fibrous root lengths among the three typical hygrophytes under long term flooding, but the main root length was greater than fibrous root length under drought. Under longterm flooding, the main root weight of the three hygrophytes was decreased in the order of C. cinerascens > P. arundinacea > A. selengensis, while the fibrous root weight was decreased in the order of C. cinerascens > A. selengensis > P. arundinacea. Under drought, obvious differences were observed in the main root and fibrous root weights among the three hygrophytes. The ratios of the belowground and aboveground biomass of the hygrophytes were significantly different under longterm flooding, but not obvious under drought. Additionally, under both longterm flooding and drought, the ratios of the main root length and plant height were not significantly different among the hygrophytes. There existed good correlations between the main root and fibrous root lengths, ratios of main root length to fibrous root length, and main root weights of the hygrophytes.